Close-up showing bands of sulfate-reducing bacteria around an oxygen
bubble. The bacteria are in three flat chambers filled with
oxygen-free medium. A single oxygen bubble was brought separately
into each capillary. Bacteria density in the suspension decreases from
the left to the right picture. The red color of indicates the presence of
oxygen whereas the surrounding bacteria band appears whitish.
The bacteria bands appear more defined and dense around the
air bubble with increasing cell density. Scale bar on the left border represents 10 millimeter.